This invention pertains to a drain assembly adapted for use on a vehicle and more specifically to a generally vertically oriented drain chamber having inlet and outlet apertures at respective upper and lower ends thereof and which is adapted to retain drainage liquid within the chamber in order to create a fluid seal when a pressure differential exists between the inlet and outlet apertures.
In the art of vehicles, particularly trucks and vans with enclosed cargo areas, it is known to provide some means to provide for drainage of any liquid, such as water, that gathers in low-lying areas of the vehicle. In a van, such a drainage device could be provided at a sill area of a rear step plate. In most instances, a drainage hole is simply provided in order for the liquid to flow therethrough.
Simply providing drain holes in a low-lying step plate area of an enclosed van for example, creates various problems especially in a van having a rear roll-up door and a cargo area that is open to the vehicle driver area. For instance, when the truck is moving above a certain speed, a pressure differential can develop between the inside of the truck and the outside ambient atmosphere, with the pressure inside the truck being lower than ambient. When this pressure differential is high enough, liquid outside the vehicle can collect inside the truck by being siphoned through the drainage holes or seeping between a seal located along the bottom of a roll-up door and a step plate. If only a drainage hole as known in the prior art is provided, this collected water can be sprayed onto the cargo floor by the air flowing through the hole into the low pressure cargo area. In addition, during the summer and winter seasons, a substantial temperature differential can exist between the inside of the truck and the outside of the truck. This siphoning effect creates a forced heat transfer circulation between the inside and outside of the truck which is undesirable, especially at relatively high speeds.
There exists a need for a drainage arrangement that can be utilized between areas having a pressure differential therebetween which will prevent liquid from being siphoned from the high pressure area to the low pressure area by creating a liquid seal therebetween. Such a drainage and seal arrangement can be utilized in various arts.
It is therefore the object of the present invention to provide a drainage assembly capable of creating a liquid seal between two areas between which a pressure differential is created. It is a further object of the present invention to provide a drain assembly which is passive, not requiring moving parts; which may be readily cleaned, if necessary; may be easily retrofitted for use in various environments; and which will function in a simple and reliable manner.